1. Field of the Invention
The present invention relates to a nonaqueous electrolyte battery, a battery pack using the nonaqueous electrolyte battery and a vehicle using the battery pack.
2. Description of the Related Art
Along with miniaturization of, for example, personal computers, video cameras and portable telephones, nonaqueous electrolyte batteries have been put to practical use and widely spread in the fields of information relevant devices and communication devices as the power sources because they have high energy density. Meanwhile, in the field of vehicles, it is desired to develop electric motor vehicles as quickly as possible because of environmental and resource problems and studies are being made also as to nonaqueous electrolyte batteries as the power sources of these electric motor vehicles.
for the power source of these electric motor vehicles to have a high energy density and, specifically, to have a high discharge capacity per unit weight or unit volume. Then, even in the case where large current is input in a moment to recover the kinetic energy in the decelerating stage as the electric power, it is demanded of these secondary batteries to have the ability of charging efficiently. These batteries also need to have the ability to output large power, and specifically, to discharge large current in a moment, when the vehicles start, abruptly move or abruptly accelerate. In short, the secondary batteries used as the power sources of electric motor vehicles are desired not only to have a large capacity but also to have good performance of inputting and outputting power in a short time.
As the technologies used to improve the performance of inputting and outputting power of nonaqueous electrolyte batteries in a short time, technologies are known in which a nonaqueous electrolyte battery and an electric double layer capacitor are combined to constitute a hybrid element as described in JP-A 10-294135 (KOKAI). These technologies have the intention of increasing the time constant of the hybrid element by the capacitive component of the electric double layer capacitor to decrease a variation in voltage in a short time, thereby improving inputting and outputting performance in a short time at low temperature.